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V/Q Mismatch


Updated May 19, 2014

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Definition: A defect which occurs in the lungs whereby ventilation (the exchange of air between the lungs and the environment) and perfusion (the passage of blood through the lungs) are not evenly matched, a finding typical of COPD.

V/Q mismatch is the most common cause of hypoxemia and a component of most causes of respiratory failure.

In a patient with V/Q mismatch, there will most likely be some areas of the lungs which are better perfused that ventilated and some areas which are better ventilated than perfused. While this occurs to some degree in the normal lung, in V/Q mismatch, it is increased significantly to the point of being pathological.

In COPD, bronchospasm, mucus plugs, inflammation and airway obstruction in general worsen ventilation disrupting the balance between ventilation and perfusion.

Also Known As: ventilation/perfusion mismatch, ventilation/perfusion ratio
The doctors said that my father's pneumonia worsened his V/Q mismatch.
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